Locate model worried about uniform (7)
I believe the answer is:
situate
'locate' is the definition.
(synonyms)
'model worried about uniform' is the wordplay.
'model' becomes 'sit' (e.g. for a painting).
'worried' becomes 'ate' (something worrying may eat someone up).
'about' means one lot of letters go next to another.
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'ate' put after 'u' is 'uate'.
'sit'+'uate'='SITUATE'
(Other definitions for situate that I've seen before include "Locate" , "Position" , "Place in a particular location" , "put in context" , "station" .)