Language left Jones the architect gutted (5)
I believe the answer is:
lingo
'language' is the definition.
(informal term for language)
'left jones the architect gutted' is the wordplay.
'left' becomes 'l' (common abbreviation).
'jones the architect' becomes 'Inigo' (Inigo Jones, 1573-1652).
'gutted' suggests removing the centre (to gut something is to remove its insides).
'inigo' with its centre removed is 'ingo'.
'l'+'ingo'='LINGO'
(Other definitions for lingo that I've seen before include "Argot" , "Language (informally)" , "local dialect" , "French?" , "Johnny Foreigner speaks one" .)