Drift aloft, perhaps (5)
I believe the answer is:
float
'drift' is the definition.
(synonyms)
'aloft perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'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" .)