Look round at an unusual leg (4)
I believe the answer is:
ogle
'look' is the definition.
(ogling is a kind of looking)
'round at an unusual leg' is the wordplay.
'round' becomes 'o' (round can mean a round object**).
'at' says to put letters next to each other.
'an unusual' indicates anagramming the letters.
'leg' is an anagram of 'gle'.
'o'+'gle'='OGLE'
(Other definitions for ogle that I've seen before include "Look at inappropriately" , "Lech" , "Close scrutiny" , "Look at lecherously" , "Eye greedily" .)