Serious award given to senior … (5)
I believe the answer is:
sober
'serious' is the definition.
(similar in meaning)
'award given to senior' is the wordplay.
'award' becomes 'obe' (I've seen this in other clues).
'given to' is an insertion indicator.
'senior' becomes 'sr' (similar in meaning).
'obe' placed inside 'sr' is 'SOBER'.
(Other definitions for sober that I've seen before include "Serious, dull" , "Sensible - clear-headed" , "Unintoxicated" , "Earnest" , "Unfuddled" .)