Mess up foxtrot turn (2,3)
I believe the answer is:
go off
'turn' is the definition.
(I've seen this before)
'mess up foxtrot' is the wordplay.
'mess up' becomes 'goof' (I've seen this in another clue).
'foxtrot' becomes 'f' (phonetic alphabet: alpha, bravo, charlie etc.).
'goof'+'f'='GO-OFF'
(Other definitions for go off that I've seen before include "Fire" , "fall asleep" , "Explode" , "discharged" , "Decay - become disenchanted with" .)