Try, after tax rises, to cheer (7)
I believe the answer is:
hearten
'cheer' is the definition.
('hearten' can be a synonym of 'cheer')
'try after tax rises' is the wordplay.
'try' becomes 'hear' ('hear' can be a synonym of 'try'**).
'after tax' becomes 'net' (I've seen this before).
'rises' says the letters should be written in reverse.
'net' back-to-front is 'ten'.
'hear'+'ten'='HEARTEN'
'to' acts as a link.
(Other definitions for hearten that I've seen before include "given cheer" , "Make cheerful" , "Inspire anew" , "Buoy" , "giving cheer" .)