Swell hat flipped, put away (6)
I believe the answer is:
dilate
'swell' is the definition.
(I've seen this before)
'hat flipped put away' is the wordplay.
'hat' becomes 'lid' (lid can informally mean a hat).
'flipped' shows that the letters should be reversed in order.
'put away' becomes 'ate' (put away can mean to eat).
'lid' in reverse letter order is 'dil'.
'dil'+'ate'='DILATE'
(Other definitions for dilate that I've seen before include "Expand in detail" , "Become wider or larger as eye pupils may" , "Widen, spread out" , "Make (something) wider or more open" , "Make or become wider" .)