Like couple in song, endlessly? Strong point (5)
I believe the answer is:
forte
'strong point' is the definition.
(I know that strong point can be written as forte)
'like couple in song endlessly?' is the wordplay.
'like' becomes 'for' (I can't justify this - if you can you should give a lot more credence to this answer).
'couple in song' becomes 'tea' (as in the song Tea for Two).
'endlessly?' means to remove the last letter (I've seen 'endlessly' mean this).
'tea' with its last letter removed is 'te'.
'for'+'te'='FORTE'
Can you help me to learn more?
(Other definitions for forte that I've seen before include "Loud (mus.)" , "A thing in which someone excels" , "In music, to be played loudly" , "sort of musical passage" , "Skill" .)