Climbing southern mountains with husband in plaster (6)
I believe the answer is:
splash
'plaster' is the definition.
(thesaurus)
'climbing southern mountains with husband' is the wordplay.
'climbing' is a reversal indicator (in a down clue, letters climb up).
'southern' becomes 's' (abbreviation).
'mountains' becomes 'alps' (alp is a kind of mountain**).
'with' says to put letters next to each other.
'husband' becomes 'h'.
's'+'alps'='salps'
'salps' reversed gives 'splas'.
'splas'+'h'='SPLASH'
'in' is the link.
(Other definitions for splash that I've seen before include "Big media display -- bellyflop effect" , "Spatter liquid about" , "Small amount of something liquid" , "Effect of hitting water (or headlines!)" , "major news item" .)