Welsh girl shaving bottom following love letter (5)
I believe the answer is:
omega
'letter' is the definition.
(I know that omega is a type of letter)
'welsh girl shaving bottom following love' is the wordplay.
'welsh girl' becomes 'Megan' (common Welsh name).
'shaving bottom' means to remove the last letter (the bottom letter is shaved off).
'following' says to put letters next to each other.
'love' becomes 'o' (love means zero in tennis).
'megan' with its final letter taken off is 'mega'.
'mega' after 'o' is 'OMEGA'.
(Other definitions for omega that I've seen before include "Final Greek letter" , "Conclusion" , "24th Greek letter" , "completes a series" , "symbol of resistance?" .)