Smallest in the Latin Quarter (5)
I believe the answer is:
least
'smallest' is the definition.
('least' can be a synonym of 'smallest')
'latin quarter' is the wordplay.
'latin' becomes 'l'.
'quarter' becomes 'east' (I've seen this in other clues).
'l'+'east'='LEAST'
'in the' acts as a link.
(Other definitions for least that I've seen before include "Superlative form of 'little'" , "Opposite of most" , "Smallest (in significance)" , "Steal (anag)" , "Of minimal significance" .)