Small uniform daughter wears guiding signal member of the clergy (9)
I believe the answer is:
subdeacon
'member of the clergy' is the definition.
(type of clergyman)
'small uniform daughter wears guiding signal' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'daughter' becomes 'd' (genealogical abbreviation).
'wears' is an insertion indicator.
'guiding signal' becomes 'beacon' (I've seen this in another clue).
'd' put within 'beacon' is 'bdeacon'.
's'+'u'+'bdeacon'='SUBDEACON'
(Other definitions for subdeacon that I've seen before include "Assistant priest" , "One preparing vessels" , "Junior minister" .)