New term mother engendered primarily for temperature gauge (11)
I believe the answer is:
thermometer
'temperature gauge' is the definition.
(I've seen this before)
'new term mother engendered primarily' is the wordplay.
'new' is an anagram indicator.
'primarily' suggests taking the first letters.
The first letter of 'engendered' is 'e'.
'term'+'mother'+'e'='termmothere'
'termmothere' with letters rearranged gives 'THERMOMETER'.
'for' is the link.
(Other definitions for thermometer that I've seen before include "Device measuring temperature" , "Instrument for measuring temperature" , "Temperature-measuring instrument" , "Temperature gauge" , "Temperature measure" .)