Lady first to encourage and tend other ranks (7)
I believe the answer is:
eleanor
'lady' is the definition.
(I've seen this before)
'first to encourage and tend other ranks' is the wordplay.
'first to' indicates taking the first letters.
'and' means one lot of letters go next to another.
'tend' becomes 'lean' ('lean' can be a synonym of 'tend').
'other ranks' becomes 'or' (military abbreviation).
The initial letter of 'encourage' is 'e'.
'e'+'lean'+'or'='ELEANOR'
(Other definitions for eleanor that I've seen before include "woman" , "Lady" , "-- Bron, actress" , "Wife of Henry II" , "Near Leo (anag) - girl's name" .)