Enter a clue or pattern or both:
The Clue
Fasten firmly (5 letter answer)
The Answer
INFIX
Tags
Notes
The answer INFIX is so rare that it appears less than once every 2500 puzzles.
Definition
INFIX as a noun:
1. an affix that is inserted inside the word
INFIX as a verb:
1. (insert, infix, enter, introduce) = put or introduce into something; "insert a picture into the text"
2. attach a morpheme into a stem word