Sweet thing to quarrel trashing snug in pub (5,5)
I believe the answer is:
brown sugar
'sweet thing' is the definition.
(I've seen this before)
'quarrel trashing snug in pub' is the wordplay.
'quarrel' becomes 'row' (synonyms).
'trashing' is an anagram indicator (I've seen 'trash' mean this).
'in' is an insertion indicator.
'pub' becomes 'bar' (both are drinking establishments).
'snug' anagrammed gives 'nsug'.
'row'+'nsug'='rownsug'
'rownsug' going within 'bar' is 'BROWN SUGAR'.
'to' acts as a link.
(Other definitions for brown sugar that I've seen before include "Sweet thing" , "Eg, demerara" , "Kind of sweetener" , "Demerara or muscovado, for example" .)