Start early Wednesday to pet inside animal (3)
I believe the answer is:
ewe
'animal' is the definition.
(female sheep)
'start early wednesday to pet inside' is the wordplay.
'start' says to take the initial letters.
'to' means one lot of letters go next to another.
'inside' means to look at the middle letters.
The middle of 'pet' is 'e'.
The first letters of 'early wednesday' is 'ew'.
'ew'+'e'='EWE'
(Other definitions for ewe that I've seen before include "A palindromic sheep" , "Lamb's dam" , "Female in a fleece?" , "One needing pastoral care" , "Language" .)