Tell engineers poor tale (6)
I believe the answer is:
relate
'tell' is the definition.
(as in to tell or relate a story)
'engineers poor tale' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'poor' indicates anagramming the letters.
'tale' with letters rearranged gives 'late'.
're'+'late'='RELATE'
(Other definitions for relate that I've seen before include "Recite - marriage guidance organisation" , "Make a logical or casual connection" , "Do well; wave about" , "Show sympathy" , "Tell (a story)" .)