Season in which one sees adder? (6)
I believe the answer is:
summer
This clue could be a double definition.
'season in which' is the first definition.
'summer' can be an answer for 'season' (summer is a season). I am not certain of the remainder of the definition.
'adder?' is the second definition.
(I've seen this before)
'one sees' acts as a link.
Can you help me to learn more?
(Other definitions for summer that I've seen before include "'Shall I compare thee to a . . . . . .'s day?' (Shakespeare)" , "Warm season, allegedly" , "One adding up" , "Adder" , "'. . . . . . time an' the livin' is easy' (song)" .)