Couplet oaf composed is inappropriate (3,2,5)
I believe the answer is:
out of place
'inappropriate' is the definition.
(I've seen this before)
'couplet oaf composed' is the wordplay.
'composed' is an anagram indicator.
'couplet'+'oaf'='coupletoaf'
'coupletoaf' is an anagram of 'OUT-OF-PLACE'.
'is' is the link.
(Other definitions for out of place that I've seen before include "inappropriate" , "needing to be elsewhere" , "Not suited to the occasion" , "incongruous" .)