Part of window showing star now and then - shut it! (4)
I believe the answer is:
sash
'part of window' is the definition.
(part of a window frame)
'star now and then shut it' is the wordplay.
I cannot quite see how this works, but
'it' could be 'sa' (old-fashioned abbreviation for sex appeal) and 'sa' is found in the answer.
The remaining letters 'sh' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for sash that I've seen before include "Band of cloth" , "Popular band in Northern Ireland" , "Baldrick" , "Waistband - type of window" , "Ribbon as a symbol of rank" .)