Chicks originally look to pull up worm (5)
I believe the answer is:
creep
'worm' is the definition.
(I've seen this before)
'chicks originally look to pull up' is the wordplay.
'originally' indicates taking the first letters.
'look' becomes 'peer' (to peer at something is to look at it).
'to pull up' is a reversal indicator (I've seen 'pulling up' mean this).
The initial letter of 'chicks' is 'c'.
'peer' written backwards gives 'reep'.
'c'+'reep'='CREEP'
(Other definitions for creep that I've seen before include "Steal" , "Move silently and secretly" , "Walk slowly, silently" , "Slink" , "Crawl; skulk" .)