Possibly alter circuit, e.g. for this instrument (8,6)

I believe the answer is:

electric guitar

'this instrument' is the definition.
(electric guitar is a kind of instrument)

'possibly alter circuit e g' is the wordplay.
'possibly' is an anagram indicator.
'alter'+'circuit'+'e'+'g'='altercircuiteg'
'altercircuiteg' with letters rearranged gives 'ELECTRIC GUITAR'.

'for' is the link.

(Another definition for electric guitar that I've seen is " Musical instrument".)

I've seen this clue in The Telegraph.

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