Firm though, without it, the least bit wobbly (6)
I believe the answer is:
stable
'firm' is the definition.
(similar in meaning)
'without it the least bit wobbly' is the wordplay.
'without' is a deletion indicator.
'wobbly' is an anagram indicator.
'least'+'bit'='leastbit'
'leastbit' with 'it' taken away is 'leastb'.
'leastb' with letters rearranged gives 'STABLE'.
'though' acts as a link.
(Other definitions for stable that I've seen before include "Horse barn" , "Firmly balanced or fixed" , "Standing firm" , "Housing for a horse" , "Firmly-fixed; building" .)