Period wearing sportswear shows inadequacies (9)

I believe the answer is:

shortages

'inadequacies' is the definition.
(shortage is a kind of inadequacy)

'period wearing sportswear' is the wordplay.
'period' becomes 'age' (age is a kind of period).
'wearing' is an insertion indicator.
'sportswear' becomes 'shorts'.
'age' inserted into 'shorts' is 'SHORTAGES'.

'shows' is the link.

I've seen this clue in The Telegraph.

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