Trimmer elephant accommodated by modern flat (9)
I believe the answer is:
recumbent
'flat' is the definition.
(thesaurus)
'trimmer elephant accommodated by modern' is the wordplay.
'trimmer elephant' becomes 'umb' (I am not sure about this - if you are sure you should believe this answer much more).
'accommodated by' indicates putting letters inside.
'modern' becomes 'recent' (I've seen this before).
'umb' going into 'recent' is 'RECUMBENT'.
Can you help me to learn more?
(Other definitions for recumbent that I've seen before include "Lying down comfortably" , "flat?" .)