Short fellow apparently embarrassed about sex (6)
I believe the answer is:
gender
'sex' is the definition.
(synonyms)
'short fellow apparently embarrassed' is the wordplay.
'short' means to remove the last letter.
'fellow' becomes 'gent' (synonyms).
'apparently embarrassed' becomes 'der' (I am not sure about this - if you are sure you should believe this answer much more).
'gent' with its last letter taken off is 'gen'.
'gen'+'der'='GENDER'
'about' acts as a link.
Can you help me to learn more?
(Other definitions for gender that I've seen before include "Sexual status" , "Class such as female or male" , "Eg, male" , "Sex category" , "Masculine, feminine or neuter" .)