Husband's not about to follow extremely pithy language (6)
I believe the answer is:
python
'language' is the definition.
(python is a programming language)
'husband's not about to follow extremely pithy' is the wordplay.
'husband' becomes 'h'.
'about' indicates an anagram.
'to follow' says to put letters next to each other.
'extremely' means to remove the middle letters.
'pithy' with its centre taken out is 'py'.
'h'+'not'='hnot'
'hnot' anagrammed gives 'thon'.
'thon' after 'py' is 'PYTHON'.
(Other definitions for python that I've seen before include "Snake that kills its prey by squeezing" , "Constrictor snake" , "Large snake that crushes and swallows its prey" , "Heavy-bodied snake" , "Dragon killed by Apollo at Delphi" .)