Partners who dance up in close formation (7)
I believe the answer is:
couples
'partners who dance' is the definition.
I can't tell whether this defines the answer.
'up in close formation' is the wordplay.
'in' is an insertion indicator.
'formation' indicates an anagram.
'close' with letters rearranged gives 'coles'.
'up' placed into 'coles' is 'COUPLES'.
Can you help me to learn more?
(Other definitions for couples that I've seen before include "Pairs" , "People with their partners" .)