Use a cover, say ... (5)

I believe the answer is:

avail

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'use' is the definition.
(I know this)

'a cover say' is the wordplay.
'cover say' becomes 'vail' (I can't justify this - if you can you should give a lot more credence to this answer).
'a'+'vail'='AVAIL'

Can you help me to learn more?

(Other definitions for avail that I've seen before include "Be of help or advantage" , "Medal (informal)" , "See 3" , "(Of no) use or benefit" , "Provide help; profit" .)

I've seen this clue in The Irish Independent.

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