Woman partnered with serviceman, getting old quite slowly (6)
I believe the answer is:
adagio
'quite slowly' is the definition.
(musical term)
'woman partnered with serviceman getting old' is the wordplay.
'woman' becomes 'Ada' (woman's name).
'partnered with' says to put letters next to each other.
'serviceman getting' becomes 'gi' (I can't explain this - if you can you should give a lot more credence to this answer).
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'ada'+'gi'+'o'='ADAGIO'
Can you help me to learn more?
(Other definitions for adagio that I've seen before include "Slowly, from a conductor" , "Musically, in slow time" , "(A movement) to be played slowly" , "' - - for Strings' (Barber)" , "In music, leisurely" .)