Pair of creatures, big and small, that makes a bond (7)
I believe the answer is:
sealant
'bond' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for sealant that I've seen before include "Material for plugging leaks" , "Material for making airtight or watertight" , "Filler used to close a gap" , "Material used for an airtight or watertight join" , "Material to prevent leakage" .)