Orchestra's leader managed to acquire good keyboard instrument (5)
I believe the answer is:
organ
'keyboard instrument' is the definition.
(I've seen this before)
'orchestra's leader managed to acquire good' is the wordplay.
'leader' says to take the initial letters.
'managed' becomes 'ran' (I've seen this before**).
'to acquire' is an insertion indicator.
'good' becomes 'g' (abbreviation).
The first letter of 'orchestras' is 'o'.
'ran' placed around 'g' is 'rgan'.
'o'+'rgan'='ORGAN'
(Other definitions for organ that I've seen before include "notes issue from this" , "Bodily part or large musical instrument" , "Eg, heart, liver" , "Large musical instrument often heard in church" , "Medium; body part" .)