Force one female in case of adultery to turn sour (7)
I believe the answer is:
acidify
'turn sour' is the definition.
(I've seen this in another clue)
'force one female in case of adultery' is the wordplay.
'force' becomes 'cid' (abbreviation for Criminal Investigation Department).
'one' becomes 'I' (Roman numeral).
'female' becomes 'f' (common abbreviation).
'in' is an insertion indicator.
'case of' suggests removing the centre (outsides of).
'adultery' with its middle taken out is 'ay'.
'cid'+'i'+'f'='cidif'
'cidif' put into 'ay' is 'ACIDIFY'.
'to' acts as a link.
(Another definition for acidify that I've seen is " Make sour".)