Squatter in store - that is right (8)
I believe the answer is:
stockier
'squatter' is the definition.
('stocky' can be a synonym of 'squat')
'store that is right' is the wordplay.
'store' becomes 'stock' (synonyms).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'right' becomes 'r' (common abbreviation).
'stock'+'ie'+'r'='STOCKIER'
'in' is the link.
(Other definitions for stockier that I've seen before include "more sturdy?" , "squatter?" , "having more beef" .)