Catch two short of a dozen, and cheer (7)
I believe the answer is:
hearten
'cheer' is the definition.
(I know that cheer can be written as hearten)
'catch two short of a dozen' is the wordplay.
'catch' becomes 'hear' (to catch something is to hear it being spoken).
'two short of a dozen' becomes 'ten' (a dozen is 12).
'hear'+'ten'='HEARTEN'
'and' acts as a link.
(Other definitions for hearten that I've seen before include "given cheer" , "Inspire anew" , "Inspirit" , "Make (someone) more confident" , "giving cheer" .)