Reserve and hog accommodation that's under way (7)
I believe the answer is:
modesty
'reserve' is the definition.
(I know that reserve can be written as modesty)
'hog accommodation that's under way' is the wordplay.
'hog accommodation' becomes 'sty' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'that's under' is a charade indicator (letters next to each other) (below, in a down clue).
'way' becomes 'mode' (synonyms).
'sty' after 'mode' is 'MODESTY'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for modesty that I've seen before include "Unassumingness" , "Humility; decency" , "Decorum, shyness" , "lack of vanity" , "Diffidence" .)