Exam's first question was worrying, second is deemed comparable (7)
I believe the answer is:
equates
'is deemed comparable' is the definition.
'exam's first question was worrying second' is the wordplay.
'first' indicates taking the first letters.
'question' becomes 'qu'.
'was worrying' becomes 'ate' (eat can mean to worry or distress).
'second' becomes 's' (common abbreviation**).
The initial letter of 'exams' is 'e'.
'e'+'qu'+'ate'+'s'='EQUATES'
(Other definitions for equates that I've seen before include "Corresponds, matches" , "Considers to be equal or equivalent" , "Regards as identical" .)