See an old archbishop as a boy (5)
I believe the answer is:
claud
'a boy' is the definition.
(I've seen this before)
'see an old archbishop' is the wordplay.
'see' becomes 'C' (the word for the letter, according to Chambers).
'an old archbishop' becomes 'Laud' (William Laud, Archbishop of Canterbury 16331645).
'c'+'laud'='CLAUD'
'as' acts as a link.
(Other definitions for claud that I've seen before include "Man" , "Boy" .)