Possibly one's pet dance in former years (3-4)
I believe the answer is:
one-step
'dance in former years' is the definition.
'one step' can be an answer for 'dance' (I've seen this before). I am not certain of the 'in former years' bit.
'possibly one's pet' is the wordplay.
'possibly' indicates an anagram.
'ones'+'pet'='onespet'
'onespet' anagrammed gives 'ONE-STEP'.
Can you help me to learn more?
(Other definitions for one-step that I've seen before include "Kind of foxtrot" , "Foxtrot's precursor" , "(Very short?) ballroom dance" , "Vigorous dance" , "Style of foxtrot" .)