Drift aloft, perhaps (5)
I believe the answer is:
float
'drift' is the definition.
(synonyms)
'aloft perhaps' is the wordplay.
'perhaps' indicates an anagram.
'aloft' anagrammed gives 'FLOAT'.
(Other definitions for float that I've seen before include "Be buoyant" , "Not sink" , "Drift aimlessly" , "Petty cash - rest on a liquid's surface" , "Petty cash - milk vehicle - fishing aid" .)