Crept off after exercise - I have to be discerning (10)

I believe the answer is:

perceptive

'be discerning' is the definition.
(synonyms)

'crept off after exercise i have' is the wordplay.
'off' is an anagram indicator.
'after' says to put letters next to each other.
'exercise' becomes 'pe' (Physical Education).
'i have' becomes 'I've' (contraction of 'I have').
'crept' is an anagram of 'rcept'.
'rcept' after 'pe' is 'percept'.
'percept'+'ive'='PERCEPTIVE'

'to' is the link.

(Another definition for perceptive that I've seen is " Aware".)

I've seen this clue in The Daily Express.

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