Tense success achieving double ... (4)
I believe the answer is:
twin
'double' is the definition.
(I've seen this before)
'tense success' is the wordplay.
'tense' becomes 't' (abbreviation used in many dictionaries).
'success' becomes 'win'.
't'+'win'='TWIN'
'achieving' acts as a link.
(Other definitions for twin that I've seen before include "indistinguishable from the next?" , "One of Gemini" , "One of two conceived together" , "One of two duplicates" , "Identical or very similar" .)