Closure by Chalicea

A message in two languages can be found in the completed grid, and is relevant to both sets of clues and the grid itself.  The wordplay in down clues leads to the answer plus an extra letter not to be entered.  These letters spell out an instruction to be applied to one grid entry.

Across
    1    Lines on a farm and animals (6)
    5    Little bird's springiness locally in the morning (6)
    9    Funeral ceremonies of old country girl (4)
    10    Scots go about after artificial language in Tropical America (7)
    11    Pine in wind encircled by rock (6)
    13    Idly earned old bob (6)
    14    Regularly payers intuit carat of fool's gold (7)
    15    Lacking ability in a punt in trouble (5)
    16    Good for certain concealed power (7)
    17    Jerkily poled a small pleasure boat (6)
    18    Confine English Internet service provider (6)
    21    Pacific sea witch one caught (and decapitated!) (6)
    24    Performer in arena raged before gold returned (6)
    27    Conscious aging saint at heart (7)
    29    Top of chapter not about religious instruction (5)
    31    Singular joint enclosure in country cowhouse (7)
    32    Sex appeal in a French folie, heartless, not trustworthy (6)
    33    Highlanders' way with a posh cake (6)
    34    Somewhat evasive cad without heart to enjoy (3-4)
    35    Cherry is wonderful, old and rare? Not so! (4)
    36    Regretted all Glaswegian square dances (6)
    37    For a cry of grief, dead end (6)
 Down
    1    Unstable lapsed unionist in preparatory time (4-2)
    2    Element, not carbon, right for harness maker (7)
    3    Man clutching rickety kilo pail, cook might find it useful (4,3)
    4    Spear-thrower's data including length, time and bit of luck (6)
    5    Colour in old prayer stained according to poet (6)
    6    Tree converted into one wagon? Quite the reverse (5)
    7    Religious text that ran awry (6)
    8    Wave of whirling caramel (6)
    10    Scots not to shoot young grouse dead in wartime (5)
    12    Ordinary working hours in room in harem (3)
    19    He'll welcome victory locally, having intermittently lost heart (7)
    20    Herb found in local seaweed and seabird dung (7)
    21    One that springs out of convoluted fissures, lacking force (6)
    22    Space is the sheltered side to set apart (6)
    23    Angry Tiger initially quitting wedge lengthens clubs (6)
    24    Canvas material not accepted for basic unit of money (5)
    25    Hearts involved in reverence for resistance (6)
    26    Men thought about impedance for son's good principle (6)
    28    Shoulder spread formerly including latitude (5)
    30    Twice trimmed reediest stop (3)
To enter this competition, send your entry as an image or in list format, indicating the final step, to quiz.man@ntlworld.com before the 8th July 2012. The first correct entry drawn from the hat will receive a copy of  one of the Chambers range of books which has been donated by Chambers.