Resolve to be complicated now? (7)

I believe the answer is:

explain

'resolve' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for explain that I've seen before include "Describe" , "Give reasons for" , "Make intelligible and account for" , "Elucidate, make clear" , "Spell out" .)

I've seen this clue in The Guardian.

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