Encountered wealthy husband escaping measurement system (6)
I believe the answer is:
metric
'measurement system' is the definition.
(I've seen this in another clue)
'encountered wealthy husband escaping' is the wordplay.
'encountered' becomes 'met' ('meet' can be a synonym of 'encounter').
'wealthy' becomes 'rich' (similar in meaning).
'husband' becomes 'h' (abbreviation).
'escaping' suggests deleting specific letters.
'rich' with 'h' taken out is 'ric'.
'met'+'ric'='METRIC'
(Other definitions for metric that I've seen before include "Quantitative" , "Like the SI system" , "Relating to poetic rhythm" , "Relating to the standard European system of measurement" , "Successor to imperial (system)" .)