A 'suit' to change into! (6)

I believe the answer is:

I believe this is a double definition.

'a suit' is the first definition.
(thesaurus)

'change into' is the second definition.
(thesaurus)

'to' acts as a link.

(Other definitions for become that I've seen before include "Grow to be", "Flatter", "Evolve into; suit", "Metamorphose into it", "Suit; turn into".)

I've seen this clue in Evening Standard.