Boy holding breath in the town (7)
I believe the answer is:
swindon
'town' is the definition.
(I've seen this before)
'boy holding breath' is the wordplay.
'boy' becomes 'son' (synonyms).
'holding' is an insertion indicator.
'breath' becomes 'wind' (wind is a kind of breath).
'son' enclosing 'wind' is 'SWINDON'.
'in the' is the link.
(Other definitions for swindon that I've seen before include "Large Wiltshire railway town" , "22 [WILTS] town" , "English town" .)