I tend Eric's terrible rash (10)
I believe the answer is:
indiscreet
'rash' is the definition.
(thesaurus)
'i tend eric's terrible' is the wordplay.
'terrible' indicates anagramming the letters.
'tend'+'erics'='tenderics'
'tenderics' is an anagram of 'ndiscreet'.
'i'+'ndiscreet'='INDISCREET'
(Other definitions for indiscreet that I've seen before include "Too ready to tell secrets" , "Ill-judged" , "Tactless" , "Reckless" , "Too ready to reveal secret things" .)