Belief held by mediocre doctors (5)

I believe the answer is:

credo

'belief' is the definition.
(credo is a kind of belief)

'held by mediocre doctors' is the wordplay.
'held by' says the answer is hidden in the clue.
'CREDO' can be found hidden inside 'mediocre doctors'.

(Other definitions for credo that I've seen before include "ideology" , "I believe in Latin" , "Guiding principles" , "Statement of guiding aims" , "Set of principles" .)

I've seen this clue in The Telegraph.

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