E.g. insert mobile numbers (8)
I believe the answer is:
Here is my best explanation:
'numbers' is the definition.
'e g insert mobile' is the subsidiary indication.
'mobile' is an anagram indicator.
'eginsert' is an anagram of 'integers'.
(Other definitions for integers that I've seen before include "Steering (anag)", "Whole numbers, not fractions" and "Steering in whole numbers".)