Sheep stuck in the well (3)
I believe the answer is:
ewe
'sheep' is the definition.
(I've seen this before)
'stuck in the well' is the wordplay.
'stuck in' says the answer is hidden in the clue.
'EWE' can be found hidden inside 'the well'.
(Other definitions for ewe that I've seen before include "Lamb's mother" , "A palindromic sheep" , "Ruminant" , "Lamb's dam" , "Partner to ram" .)