At Gateshead, a defeat to smooth over as best possible (5)
I believe the answer is:
gloss
'smooth over as best possible' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'at gateshead a defeat' is the wordplay.
'at' means one lot of letters go next to another.
'gateshead' becomes 'g' (head letter of 'gates').
'a defeat' becomes 'loss' (I've seen this before**).
'g' put next to 'loss' is 'GLOSS'.
'to' is the link.
Can you help me to learn more?
(Other definitions for gloss that I've seen before include "marginal note" , "translation" , "Provide explanations" , "Shine, lustre" , "High shine" .)