Faint, without disturbing younger family member (5)
I believe the answer is:
swoon
'faint' is the definition.
(synonyms)
'without disturbing younger family member' is the wordplay.
I cannot quite see how this works, but
'without' could be 'wo' (abbreviation of 'without', normally with a slash) and 'wo' is located in the answer.
'family member' could be 'son' (I've seen this in other clues) and 'son' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for swoon that I've seen before include "experience ecstasy" , "Faint (with emotion)" , "Fall fainting" , "Display of extreme emotion" , "Lose consciousness" .)