She has Albert's initial on her undergarment (5)
I believe the answer is:
vesta
'she has albert's initial' is the definition.
I can't tell whether this definition defines the answer.
'on her undergarment' is the wordplay.
'on' means one lot of letters go next to another.
'her' becomes 'a' (I can't justify this - if you can you should believe this answer much more).
'undergarment' becomes 'vest' (vest is a kind of undergarment).
'a' put after 'vest' is 'VESTA'.
Can you help me to learn more?
(Other definitions for vesta that I've seen before include "Hearth goddess; a match" , "heavenly body" , "Asteroid; goddess; match" , "Stave (anag.)" , "Roman goddess; match" .)