More thickset farm animals? That is right (8)
I believe the answer is:
stockier
'more thickset' is the definition.
('stocky' can be a synonym of 'thickset')
'farm animals? that is right' is the wordplay.
'farm animals?' becomes 'stock' (stock can mean farm animals).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'right' becomes 'r' (common abbreviation).
'stock'+'ie'+'r'='STOCKIER'
(Other definitions for stockier that I've seen before include "more sturdy?" , "having more beef" , "squatter?" .)