Go off melon, maybe, unpleasant at first for the tongue (4)
I believe the answer is:
urdu
'the tongue' is the definition.
(Urdu is an example)
'go off melon maybe unpleasant at first' is the wordplay.
'off' is a deletion indicator.
'melon maybe' becomes 'gourd' (melon is a type of gourd).
'unpleasant at first' becomes 'u' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'gourd' with 'go' taken away is 'urd'.
'urd'+'u'='URDU'
'for' is the link.
(Other definitions for urdu that I've seen before include "One of official languages of Pakistan" , "Official language used in Pakistan" , "Indic language written in Persian script" , "Pakistani language" , "Language spoken by Moslems in Pakistan and India" .)