She’s a bit of an eyeful! (4)
I believe the answer is:
iris
'she's' is the definition.
(I've seen this before)
'an eyeful' is the wordplay.
'an' becomes 'i' (Roman numeral for one).
'eyeful' becomes 'ris' (I can't justify this - if you can you should give a lot more credence to this answer).
'i'+'ris'='IRIS'
'a bit of' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for iris that I've seen before include "Bright flower or eye part" , "Ms Murdoch" , "Flag,flower and part of the eye" , "Woman" , "Eye diaphragm" .)