Not favouring big stove in small tenement, ultimately (7)
I believe the answer is:
against
'not favouring' is the definition.
(I've seen this before)
'big stove in small tenement ultimately' is the wordplay.
'big stove' becomes 'aga' (I've seen this before. I am not sure about the 'big' bit.).
'small' becomes 's' (abbreviation - e.g. clothes size).
'ultimately' says to take the final letters.
The last letter of 'tenement' is 't'.
'aga'+'in'+'s'+'t'='AGAINST'
Can you help me to learn more?
(Other definitions for against that I've seen before include "V" , "Opposed" , "In opposition to" , "Not favouring" , "close by" .)