Head I trapped between two legs (5)
I believe the answer is:
onion
'head' is the definition.
(I've seen this in other clues)
'i trapped between two legs' is the wordplay.
'two legs' can mean two substitutions for 'leg'.
'trapped between' is an insertion indicator.
'leg' becomes 'on' (cricket term, fielding positions).
'leg' becomes 'on' (cricket term, fielding positions).
'on'+'on'='onon'
'i' going inside 'onon' is 'ONION'.
(Other definitions for onion that I've seen before include "One may be set" , "it can bring tears" , "Shape of Russian dome" , "Alliaceous plant" , "one understood by expert" .)