Initially nervous: when turning to drink, gains a little extra confidence (12)

'confidence' is the definition.

'initially nervous when turning to drink gains a little extra' is the wordplay.
I cannot quite understand how this works, but
'when' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
'drink' could be 'guinness' (Guinness is a type of stout) and 'guinness' is present in the leftover letters.
'a' could be 'an' and 'an' is present in the answer.
A single letter 's' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...