Look ~n there's an opening for an egghead! (4)
I believe the answer is:
gape
'look' is the definition.
(gaping is a kind of looking)
'there's an opening for an egghead' is the wordplay.
'there's an opening' becomes 'gap' (gap is a kind of opening).
'for' is a charade indicator (letters next to each other).
'an egghead' becomes 'e' (head letter of 'egg').
'gap'+'e'='GAPE'
'n' is the link.
(Other definitions for gape that I've seen before include "watch in wonder" , "Look in amazement or stupidity" , "Stare stupidly" , "Look amazed" , "Gawp" .)