Nation follows expert in male gland (8)
I believe the answer is:
prostate
'male gland' is the definition.
'prostate' can be an answer for 'gland' (prostate gland is a kind of gland). I'm not sure about the 'male' bit.
'nation follows expert' is the wordplay.
'nation' becomes 'state' (synonyms).
'follows' says to put letters next to each other.
'expert' becomes 'pro' (short for professional).
'state' put after 'pro' is 'PROSTATE'.
'in' acts as a link.
Can you help me to learn more?
(Another definition for prostate that I've seen is " A protest about a troublesome male gland".)