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' indicates an anagram (I've seen 'trash' mean this).
'in' means one lot of letters goes inside another.
'pub' becomes 'bar' (both are drinking establishments).
'snug' with letters rearranged gives 'nsug'.
'row'+'nsug'='rownsug'
'rownsug' put inside 'bar' is 'BROWN SUGAR'.
'to' is the link.
(Other definitions for brown sugar that I've seen before include "Sweet thing" , "Eg, demerara" , "Kind of sweetener" , "Demerara or muscovado, for example" .)