Steady second counter (6)
I believe the answer is:
stable
'steady' is the definition.
(similar in meaning)
'second counter' is the wordplay.
'second' becomes 's' (common abbreviation).
'counter' becomes 'table' (I've seen this before).
's'+'table'='STABLE'
(Other definitions for stable that I've seen before include "Fixed; secure" , "Firm and dependable" , "Equine housing" , "'Steady, not given to sudden change (6)'" , "Sound" .)